Apparatus for improved subaqueous stability

ABSTRACT

A locomotive element to be incorporated in an underwater device propelled on a supporting surface along a predetermined axis of motion. The locomotive element comprises at least one resilient surface that can be rolled on the supporting surface. The resilient surface has a plurality of flow-through passages substantially perpendicular to the axis of motion.

FIELD OF THE INVENTION

The present invention relates to the stability of subaqueous tractionvehicles. More particularly, it relates to an apparatus for improvingthe stability of underwater propelled devices, like swimming poolcleaning robots.

BACKGROUND OF THE INVENTION

There are many types of automatic pool cleaners available, exhibitingvarious navigational abilities and ways of cleaning the bottom of apool.

For example, in U.S. Pat. No. 6,125,492 (Prowse), titled AUTOMATICSWIMMING POOL CLEANING DEVICE, there was disclosed an automatic swimmingpool cleaning device, which includes a flexible cleaning member designedto contact an underwater surface of the swimming pool. A tube is coupledto the cleaning member for connecting to the cleaning device to a watervacuum hose via hose adapter. Water and pool surface contamination isdrawn from underneath the cleaning member up through the tube by suctionto a water filter system before being returned to the pool. A flexiblevalve member is mounted proximate a throat region of the tube wherein aswater is drawn up through the tube a decrease in pressure in the throatregion causes the valve member to flex and momentarily interrupt theflow of water. The interruption to the flow of water through the tuberesults in a momentary differential of ambient pressure underneath theflexible cleaning member which enables the device to move forwardsincrementally along the underwater surface of the pool.

U.S. Pat. No. 6,099,658 (Porat), titled APPARATUS AND METHOD OFOPERATION FOR HIGH-SPEED SWIMMING POOL CLEANER disclosed an apparatusand method for cleaning the bottom and vertical side walls of a swimmingpool, pond or tank employing a robotic, self-propelled cleaner. Therobot has a protective housing of conventional design, the cleaner beingoperated at a primary cleaning speed as it traverses the surfaces to becleaned and until the cleaner housing emerges from the water along asidewall of the pool; thereafter the cleaner operates at a secondarydrive speed that is relatively slower than the primary speed and thecleaner thereafter reverses direction and descends for a pre-determinedperiod of time at the slower secondary speed in order to permit the airentrained under the housing to escape without destabilizing the cleanerduring descent. After the predetermined period of time, the cleanerresumes operation at the more rapid primary speed until the cleanerhousing once again emerges from the water's surface, after which thecycle is repeated.

In U.S. Pat. No. 5,086,535 (Grossmeyer et al.) titled MACHINE AND METHODUSING GRAPHIC DATA FOR TREATING A SURFACE, there was disclosed a machinefor treating a surface area within a boundary perimeter includes a selfpropelled chassis having a surface treating device mounted on it. Acomputing section is mounted on the chassis and a powered wheel (or eachof plural powered wheels) has a motor module for receiving commandsignals from the computing section. A position sensor is coupled to thecomputing section for generating a feedback signal representing theactual position of the machine. A data loading device coacts with thecomputing section for transmitting data to such computing section. Adata file stores graphic data developed from a graphic depictionrepresenting the surface area to be treated as well as other datadeveloped in other ways. The data file coacts with the computing sectionand transmits graphic and other data to it. The computing section isarranged for processing the data and the feedback signal andresponsively generating command signals directed to each motor module.Such modules, and the motors controlled thereby, propel the machine overthe surface area selected to be treated.

U.S. Pat. No. 5,569,371 (Perling) titled SYSTEM FOR UNDERWATERNAVIGATION AND CONTROL OF MOBILE SWIMMING POOL FILTER, disclosed anunderwater navigation and control system for a swimming pool cleaningrobot, having a driver, an impeller, a filter and a processor forcontrolling the driver and a signal-producing circuit. The systemfurther includes a signal-detecting circuit mounted on the pool, aninterface located on the ground in proximity to the pool and comprisinga detector for receiving and processing data from the detecting circuitand for transmitting signals to the robot's processor. Determination ofthe actual robot location is performed by triangulation in which thestationary triangulation base is defined by at least two spaced-apartsignal detectors and the mobile triangle apex is constituted by thesignal-producing circuit carried by the robot.

U.S. Pat. No. 5,197,158 (Moini) titled SWIMMING POOL CLEANER, discloseda vacuum powered automatic swimming pool cleaning device having a hollowhousing supported on two pairs of device mover wheels. The housingincludes a central water suction chamber in water flow communicationwith a water suction trough at the bottom of the housing and in wateroutlet communication with an external vacuum line, a gear train fordriving one of the pairs of mover wheels, and pivoted directionalcontrol floats. The water suction chamber houses an axle mounted turbinewheel bearing water driven vanes with the turbine being rotated in onedirection only by water flow through the chamber. The turbine axle bearsa turbine power output drive gear which intermeshes with one or theother of two shift gears which in turn reversibly drive the gear trainas dictated by the position of the directional control floats within thehousing. The floats swing shift within the housing to shift the shiftgears in response to the impact of the cleaning device on an obstructionon the pool floor or by the device impacting a vertical pool wall. Theswing shift of the control floats reverses the rotation of the moverwheels and thus the direction of movement of the cleaning device on thepool floor.

U.S. Pat. No. 4,786,334 (Nystrom) titled METHOD OF CLEANING THE BOTTOMOF A POOL, disclosed a method of cleaning the bottom of a pool with theaid of a pool cleaner. The pool cleaner travels along the bottom of thepool and collects material lying at the bottom of the pool. The poolcleaner is arranged to travel to and fro in straight, parallel pathsbetween two opposite walls of the pool. At the walls the pool cleaner isturned by rotating a half turn so that, after turning, it will have beendisplaced laterally perpendicular to the initial direction of travel.

In U.S. Pat. No. 4,593,239 (Yamamoto) titled METHOD AND APPARATUS FORCONTROLLING TRAVEL OF AN AUTOMATIC GUIDED VEHICLE, there was disclosedan automatic guided vehicle detects marks located on a plurality ofpoints along a route it travels using at least three sensors, selectsthe number of marks detected from each individual sensor as a referencevalue in accordance with the logic of majority, and stops when thereference value agrees with a predetermined value. Cumulative errors,caused by misdetection are thus avoided and, there is little cumulativeerror.

U.S. Pat. No. 4,700,427 (Kneppers), titled METHOD OF AUTOMATICALLYSTEERING SELF-PROPELLED FLOOR-CLEANING MACHINES AND FLOOR-CLEANINGMACHINE FOR PRACTICING THE METHOD, disclosed a method of automaticallysteering a self-propelled floor-cleaning machine along a predeterminedpath of motion on a limited area to be worked. A sequence of pathsegments stored in a data memory is retrieved, and the path segmentstraveled by the machine. Markings are recognized by at least one sensorand converted into course-correcting control commands actuating and/orsteering the machine.

U.S. Pat. No. 3,979,788 (Strausak) titled MOBILE MACHINE FOR CLEANINGSWIMMING POOLS, disclosed a mobile machine for cleaning swimming poolsby suction removal of sediment from the bottom of the swimming poolscomprises a water turbine driving a drive wheel in such a way that themachine follows a self-steered path on the bottom of the swimming pools.The drive wheel is capable of rotating about a vertical steering axle toprevent the machine from becoming blocked at a wall or in a corner ofthe swimming pools.

It is noted that covering efficiently and quickly the bottom (and sidewalls) of a swimming pool is not simple a task, and various scanningalgorithms (see some of the above-mentioned patents for examples) weredevised to try and overcome this complex problem. Contributing to thecomplexity of the navigational problem is the fact that even though arobot is generally programmed to travel in straight lines from side toside and take accurate turns, it is difficult to keep it on such pathand turns are hard to direct accurately. In fact a travel pattern of apool cleaning robot is more likely to be deviated as the robot issubjected to different conditions and forces such as its own weight, thepull and weight of its electric cord (if there exist one), underwatercurrents, different friction forces due to uneven surface elevation ortexture, dirt on floor, asymmetrically (or even amorphically) shapedpools etc. A further factor that reduces the robot's traction is thefact that as the wheels or tracks of the robot turn, they drag a thinfilm of water underneath themselves, contributing to a hydroplaningeffect.

Consequently it is desirable to introduce an apparatus that contributesto the stability of a pool cleaning robot.

It is the purpose of the present invention to provide a novel andimproved apparatus for adding to the stability of an underwaterpropelled device, for example, a pool cleaning robot traveling on thebottom and side walls of a swimming pool.

Another aim of the present invention is to provide such an apparatusthat enables a pool cleaning robot to better maintain its line ofmovement.

Other advantages and aspects of the present invention will becomeapparent after reading the present specification and viewing theaccompanying drawings.

BRIEF DESCRIPTION OF THE INVENTION

It is therefore thus provided, in accordance with a preferred embodimentof the present invention, a locomotive element to be incorporated in anunderwater device propelled on a supporting surface along apredetermined axis of motion, the locomotive element comprising at leastone resilient surface that can be rolled on the supporting surface, saidat least one surface having a plurality of flow-through passagessubstantially perpendicular to the axis of motion.

Furthermore, in accordance with a preferred embodiment of the presentinvention, the element is in the form of a wheel.

Furthermore, in accordance with a preferred embodiment of the presentinvention, the element is in the form of a track.

Furthermore, in accordance with a preferred embodiment of the presentinvention, the element is in the form of a drum.

Furthermore, in accordance with a preferred embodiment of the presentinvention, the flow-through passages are located in a plurality ofprotrusions provided on the resilient surface.

Furthermore, in accordance with a preferred embodiment of the presentinvention, there is provided a pool cleaning robot comprising amotorized drive; an impeller driven by a pump motor; power supply; andlocomotive elements coupled to the motorized drive for propelling therobot on a supporting surface along a predetermined axis of motion, eachof the locomotive elements comprising:

at least one resilient surface that can be rolled on the supportingsurface, said at least one surface having a plurality of flow-throughpassages substantially perpendicular to the axis of motion.

Furthermore, in accordance with a preferred embodiment of the presentinvention, each of the locomotive elements is in the form of a wheel.

Furthermore, in accordance with a preferred embodiment of the presentinvention, each of the locomotive elements is in the form of a track.

Furthermore, in accordance with a preferred embodiment of the presentinvention, each of the locomotive elements is in the form of a drum.

Furthermore, in accordance with a preferred embodiment of the presentinvention, the flow-through passages are located in a plurality ofprotrusions provided on the resilient surface.

Furthermore, in accordance with a preferred embodiment of the presentinvention, there is provided a method for enhancing stability of alocomotive element, used to propel an underwater propelled device alonga predetermined axis of motion, the method comprising:

providing the underwater propelled device with locomotive elements, eachof the locomotive elements comprising:

at least one resilient surface that can be rolled on the supportingsurface, said at least one surface having a plurality of flow-throughpassages substantially perpendicular to the axis of motion.

BRIEF DESCRIPTION OF THE FIGURES

In order to better understand the present invention, and appreciate itspractical applications, the following Figures are provided andreferenced hereafter. It should be noted that the Figures are given asexamples only and in no way limit the scope of the invention as definedin the appending claims. Like components are denoted by like referencenumerals.

FIG. 1 a illustrates a sectional view of a pool cleaning robot inaccordance with the present invention.

FIG. 1 b illustrates the bottom view of a pool cleaning robot inaccordance with the present invention.

FIG. 2 illustrates an isometric view of a pool cleaning robot wheel inaccordance with a preferred embodiment of the present invention.

FIG. 3 a illustrates a side view of a pool cleaning robot wheel inaccordance with a preferred embodiment of the present invention.

FIG. 3 b illustrates a rear view of a pool cleaning robot wheel inaccordance with a preferred embodiment of the present invention.

FIG. 4 a illustrates a side view of a pool cleaning robot belt or trackin accordance with another preferred embodiment of the presentinvention.

FIG. 4 b illustrates a side view of a pool cleaning robot belt or trackin accordance with yet another preferred embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE INVENTION AND FIGURES

A main aspect of the present invention is the provision of apool-cleaning robot with a novel and unique stabilization mechanism thathelps maintain the robot's direction of motion.

Reference is now made to FIG. 1 a illustrating a sectional view of apool cleaning robot 40 in accordance with the present invention. A robothousing 42 houses a motor drive 48 for driving the axles 44 (optionallya brush or sponge 54 may be added) on which ends wheels 46 are attachedto the caterpillar tracks, an impeller 52 oriented horizontally (to pumpwater from the pool floor upwards into the robot), driven by a pumpmotor 50 (with ingress cover 51), control unit 56, central processingunit (CPU) 58 and wall encounter sensor 60.

The pumped dirt and foliage are collected inside a filter bag that ispositioned inside the housing along the pump. Power cable 62 goesthrough the housing 42 to provide power to the robot electriccomponents. In other preferred embodiments of the present invention nopower cable is provided and instead the robot is powered by battery.

FIG. 1 b illustrates the bottom view of a pool cleaning robot inaccordance with the present invention. Twin parallel caterpillar tracks43 are provided, stretched over and motivated by wheels 46, which aremotivated by axle 44. Also attached to axles 44 are wheel elements 80.

The robot shown in FIGS. 1 a and 1 b is driven by a single motor (drivemotor 48). Usually pool cleaning robots targeted for small and mediumsized pools are provided with a single motor drive, whereas for twinmotor drive is popular in large pools cleaning robots. Single motordrive can be reversed by employing provided transmission to reverse thedirection of the rotation of the wheel axles, but it cannot be used toturn the robot sideways.

The stabilization mechanism that comprises the present invention, shownin FIG. 2, comprises a series of resilient flow-through passages 82 inthe perimeter 88 of one or more of those robot elements 80 that are incontact directly or indirectly with the pool bottom (and sides). In apreferred embodiment of the present invention the element is one or moremembers of a set wheels 90.

Passage 82 passes from one side 88 of the wheel to the other. In apreferred embodiment of the present invention, the passage isimplemented as a cavity running from one side of the wheel to the otherin a protrusion 84, the passage being open at each end. Protrusions 84are located around the perimeter of wheel element 80 and are separatedby open recesses 86. Passage 82 can equally be implemented in othermanners by one skilled in the art and still have the functionalitydescribed here. For example, passages 82 could be inserted into aperimeter without protrusions 84 and recesses 86, however these elementshave the advantage of adding traction.

Wheel element 80 fits onto an axle or other form of locomotion. (In FIG.2 the center 90 of element 80 is shaped to fit on the axle.)

As wheel element 80 turns, and a region of the perimeter with a passagein it starts to come into contact with the bottom (or sides) of thepool, the leading end of the passage is pressed closed between thebottom and the wheel by gravity and by the suction forces of the robotpump 50 (when on a side wall only the suction forces apply). Water inthe passage starts to be pushed out to either side, creating twocounterbalancing stream vectors in opposing directions perpendicular tothe plane of rotation. This continues until the cavity is completelycompressed (directly at the bottom of the rotation of the wheel). As thewheel continues to turn, the leading end of the passage is released fromcontact with the bottom, the resilient passage starts to spring back outto its original shape, and water rushes back into the passage, againcreating a pair of counterbalancing stream vectors in opposingdirections perpendicular to the plane of rotation. The stream vectorstaper off as the passage fully returns to its original volume. In bothcases, where the water is forced out and where it rushes back in, thenet result of the counterbalancing forces is to increase the stabilityof the wheel element 80, hence increasing the stability of the robot andminimizing the effects of other forces acting in directions other thanthe direction of motion on the wheel element 80.

In other words: when the passage is brought to a position between theunderwater device and the supporting surface, it is pressed closedthereby producing two outward streams through the ends in opposingdirections that are substantially perpendicular to the axis of motion,and when the passage exits the position between the underwater deviceand the supporting surface, it regains its original shape therebyproducing two inward streams through the ends in opposing directionsthat are substantially perpendicular to the axis of motion, therebyenhancing the stability of the locomotive element.

FIG. 3 a is a side view of the present invention with dotted arrowsshowing the direction of forces. Shown is the axis of motion, therotation, the force of gravity and suction, the outward force 94perpendicular to the wheel element 80 from water being forced out ofpassage 82 as protrusion 84 is compressed, and the inward force 96 fromwater flowing back into passage 82 as protrusion 84 regains its shape.Forces 94 and 96 are perpendicular to the plane of the side of the wheeland should be seen as lying on the axis coming out of the drawing (whichcannot be shown in a two dimensional drawing).

FIG. 3 b is a rear view of wheel element 80 showing forces 94 and 96.Again, force 94 derives from water being pushed out the two sides asprotrusion 84 is flattened. Force 96 derives from the oppositemechanism: as protrusion 84 regains its shape, water rushes into passage82, creating equal forces perpendicular to the plane of rotation.

The mechanism of the present invention can be implemented in variousways, the only requirement being that the element 80 is regularlycompressed and released. Typically this would be done by having element80 implemented as a rotating locomotive element in contact with the poolbottom (walls), although the compression/release could be effected bysome type of powered mechanical element.

Note that the term “locomotive element”, for the purpose of the presentinvention, refers to any kind of intermediary element between thedriving power of an underwater propelled device and the supportingsurface on which the device is propelled, which physically causes thedevice to move (e.g. wheels, tracks, drums etc.)

Element 80 may be implemented in a cylindrical form (like a drum) usedas a single locomotion element across the width of the robot (in whichcase two such wheel elements are to be used).

FIG. 4 a shows an alternative embodiment of the present invention whereelement 80 has been implemented as a caterpillar track.

FIG. 4 b shows an alternative embodiment of the present invention whereelement 80 has been implemented as drive wheels for a caterpillar track.

The stabilization mechanism of the present invention is not limited to aparticular type of swimming pool cleaning robot or particular shape,depth, or volume of swimming pool.

Note that although in the present specification and accompanyingdrawings the submerged robot was illustrated as having a single motor,the present invention is not limited to a single-motor robot. In factthe present invention is applicable to any submerged robots, with anynumber of motors or pumps.

It should be clear that the description of the embodiments and attachedFigures set forth in this specification serves only for a betterunderstanding of the invention, without limiting its scope as covered bythe following claims.

It should also be clear that a person skilled in the art, after readingthe present specification could make adjustments or amendments to theattached Figures and above described embodiments that would still becovered by the following claims.

1. A locomotive element to be incorporated in an underwater devicepropelled on a supporting surface along a predetermined axis of motion,the locomotive element comprising at least one resilient surface thatcan be rolled on the supporting surface, said at least one surfacehaving a plurality of flow-through passages substantially perpendicularto the axis of motion.
 2. The locomotive element of claim 1, wherein itis in the form of a wheel.
 3. The locomotive element of claim 1, whereinit is in the form of a track.
 4. The locomotive element of claim 1,wherein it is in the form of a drum.
 5. The locomotive element of claim1, wherein the flow-through passages are located in a plurality ofprotrusions provided on the resilient surface.
 6. A pool cleaning robotcomprising a motorized drive; an impeller driven by a pump motor; powersupply; and locomotive elements coupled to the motorized drive forpropelling the robot on a supporting surface along a predetermined axisof motion, each of the locomotive elements comprising: at least oneresilient surface that can be rolled on the supporting surface, said atleast one surface having a plurality of flow-through passagessubstantially perpendicular to the axis of motion.
 7. The robot of claim6, wherein each of the locomotive elements is in the form of a wheel. 8.The robot of claim 6, wherein each of the locomotive elements is in theform of a track.
 9. The robot of claim 6, wherein each of the locomotiveelements is in the form of a drum.
 10. The robot of claim 6, wherein theflow-through passages are located in a plurality of protrusions providedon the resilient surface.
 11. A method for enhancing stability of alocomotive element, used to propel an underwater propelled device alonga predetermined axis of motion, the method comprising: providing theunderwater propelled device with locomotive elements, each of thelocomotive elements comprising: at least one resilient surface that canbe rolled on the supporting surface, said at least one surface having aplurality of flow-through passages substantially perpendicular to theaxis of motion.